Tuning the quality factor of split nanobeam cavity by nanoelectromechanical systems.

A split nanobeam cavity is theoretically designed and experimentally demonstrated. Compared with the traditional photonic crystal nanobeam cavities, it has an air-slot in its center. Through the longitudinal and lateral movement of half part of the cavity, the resonance wavelength and quality factor are tuned. Instead of achieving a cavity with a large tunable wavelength range, the proposed split nanobeam cavity demonstrates a considerable quality factor change but the resonance wavelength is hardly varied. Using a nanoelectromechanical system (NEMS) comb-drive actuator to control the longitudinal and lateral movement of the split nanobeam cavity, the experimentally-measured change of quality factor agrees well with the simulated value. Meanwhile, the variation range of resonance wavelength is smaller than the full width at half maximum of the resonance. The proposed structure may have potential application in Q-switched lasers.